Fountain Of Puppyhood: Can New Drug Lengthen Your Dog’s Life?

Can a drug that gave mice longer lives and improved brain function work for dogs and people too? A new study plans to find out.

By Vicki Croke

Given the opportunity, would you sign your beloved dog up for a drug trial that stood the chance of adding years to his or her life (but might also have some unknown side effects)?

That’s not a hypothetical question. Researchers at the University of Washington in Seattle have just proposed a trial in which an anti-aging drug will be given to pet dogs whose owners choose to participate.

A way to lengthen the lives of dogs, even giant breed dogs like the Irish wolfhound, would be sweet for the people who love them. Photo: Vicki Croke.

The drug, rapamycin, which was originally developed as an anti-rejection drug for humans receiving kidney transplants, is pretty tempting. The substance is involved in cell growth, and, in animal trials, it’s been shown to increase the lifespan of female mice by 13 percent.

For those of us with large or giant breed dogs, longevity is an especially painful topic. Wolfhounds and great Danes are among the heartbreakers.

“All dog breeds are the same species, yet they age at very different rates,” says David Waters, DVM, PhD, professor and associate director of the Purdue University Center on Aging. “We still don’t understand why.”

The rare Mexican breed, the Xoloitzcuintle, has a life span of 15 to 20 years, for example, while the Irish Wolfhound has an estimated 6 to 8 year life expectancy….

Nearly 40% of small breed dogs live longer than 10 years, but only 13% of giant breed dogs live that long. The average 50-pound dog will live 10 to 12 years. But giant breeds such as great Danes or deerhounds are elderly at 6 to 8 years.

The researchers hope to test rapamycin in large dogs that typically live for eight to ten years; they would start giving the drug to animals aged six to nine. A pilot trial would involve about 30 dogs, half of which would receive the drug, and would allow the researchers to dose the dogs for a short time and observe effects on heart function and some other health measures. The trial could be completed in as little as three years, but researchers will know long before that — perhaps in months — whether rapamycin improves cardiac function or other aspects of health.

Rapamycin acts on a protein that is involved in cell growth, but little is known about how it extends life. It might retard the ageing process itself or it might prevent age-related diseases. One hypothesis is that it works primarily by preventing the development of cancers.

The notion that this drug may slow down the aging process and/or prevent the development of cancer is exciting. And, rapamycin, which comes from isolated bacterial products in the soil of Easter Island, may also even boost cognitive function. But, of course, there are cautions.

Rapamycin has been linked to an increased risk of diabetes in humans who’ve had kidney transplants, and other side effects could emerge.

The purpose of the trial is to get a step closer to understanding how rapamycin might work as a fountain of youth for humans. So why not just try it on people? There are a few reasons.

The drug is no longer patentable so few companies would be willing to invest in it as an anti-ageing compound. Human trials are also extremely expensive and to test if it extends a person’s lifespan would take a very long time.

Dogs have become candidates because they share our lifestyles and some of our old-age diseases.

According to Nature News:

Pet dogs should provide a more realistic test than lab mice of how the drug would work in humans. Pets experience some of the same environmental influences and get some of the same age-related diseases as their masters, says [molecular biologist Matthew] Kaeberlein. (He plans to enroll his own German shepherd dog when it is old enough.)

Other researchers say that Kaeberlein and [Daniel] Promislow’s reasoning makes sense. “We’re talking about whether aged pets will benefit, and that’s a good model for a human population,” says physiological geneticist David Harrison of the Jackson Laboratory in Bar Harbor, Maine, who has studied rapamycin in mice.

But before you answer the question of whether you’d sign your dog up for this study, it’s important to note that, as is standard, about half the dogs will receive not rapamycin, but a placebo.

3 Responses to “Fountain Of Puppyhood: Can New Drug Lengthen Your Dog’s Life?”

This is really interesting and cool. How in the world did they guess/figure that bacteria from Easter Island might have some power of rejuvenation?! Are there animals there that feed on it who live a long time?

While the results of the studies in mice are fascinating, let me inject a word or two or three of caution.
Rapamycin is used in transplant patients to suppress rejection and has some serious side effects. As an immunosuppressive drug, one of its most worrisome side effects is increased susceptibility to infection. The mice used for the studies of longevity were all of one strain (are all genetically identical, like identical twins) and were kept under standard lab conditions, not germ-free, but very clean. It is not known what the longevity effect of rapamycin would be on a mixed population of mice out in the real world, with real world infectious diseases.
The most recent and comprehensive study of rapa-treated mice:http://www.jci.org/articles/view/67674
has shown that the drug does not reverse or slow aging in general, but does slow some aging-related symptoms, which sounds, and may be, very good, but these effects are complex. E.g., rapamycin messes with glucose metabolism, sometimes in good ways, sometimes in bad depending on the circumstances, e.g. it can induce diabetes-like responses to glucose, and either cause weight gain or loss.
The normal cause of death of the particular strain of mice used in the study is cancer of the immune system or blood cells (~70% of these mice in lab conditions die of these tumors), and it appears that the main effect on longevity is to delay the appearance of these tumors. Again, this sounds great, but…. How this data, gathered on these very special animals, translates into effects on canine or human populations, with very different main causes of death, is very very far from being known.
As both an animal-lover and retired biomedical scientist, I have mixed feelings about having our animal friends make “one small step for mankind” in our stead. My primary loyalty needs to be toward my own species, so I understand that it is necessary that some animals, raised specifically for research, must be the first to experience what might be medical breakthroughs. When it comes to “volunteering” our healthy pets, essentially our family members, for experimental treatments, I find myself in a murky area. The notion of “informed consent” breaks down when the individual receiving the treatment is one who would happily and trustingly follow me to the edge of the universe.